Our Manufactured Building Adjustable Leveling and Support Device was invented in response for the critical need for a more substantial "pier" type foundation support for manufactured buildings such as factory built mobilehomes, portable classrooms, temporary office buildings, modular homes, construction site shacks, or any other type of manufactured building or structure which incorporates in its design one or more mainframe chassis members which run the length or width of the building, atop which mainframe chassis members the building or structure is fabricated.
At the present time the general method of supporting and leveling such a building or structure is to install a large number of flimsy and highly unstable steel piers which consist typically of an 8" to 12" wide square base at each corner of which is attached lengths of 3/4" to 1" pieces of angle iron which at their other ends are joined together in a pyramid shape by a collar which has a center hole that facilitates the attachment of a support head consisting of a metal plate to the bottom of which is attached a threaded rod which inserts through the center hole of the collar at the top of the pier and a nut used to adjust the height of the support head. The support head is supposed to provide support to the mainframe of the building.
The bases and legs of these piers typically are fabricated from very thin metal (0.075-0.120 avg. gage). The support heads typically consist of a 11/2".times.3" 18 gage plate attached to a 5".times.3/4" piece of threaded rod stock and an adjustment nut. The average rated capacity is about 2,500 lbs of vertical load. They are not rated for horizontal or lateral loads and have very little capacity for such loading. These piers have no center line member which carries their load directly to the ground in a straight line with the vertical load they support. All vertical bearing capacity is borne along the four legs to the corners of the square base at a tangent angle to the load, a very inefficient and undesirable load bearing configuration compared to the direct, straight line load transfer to ground of our device. Resistance of these currently used piers to tilting and tipping is minimal at best. The typical standard pier has a leg angle to base ranging from 60 to as much as 75 degrees. The typical height from base to tip of the pyramid exceeds the width of the base by at least 2 to 1 giving the device a small base and tall height which tends to make the device subject to being easily tipped over when it is subjected to any sort of sideward motion or stress. Once this tipping motion is started, the load is immediately transferred to only one or two of the four legs which immediately causes at least a doubling or more of the load moment on those legs depending on the amount of sideward load acceleration. This circumstance many times results in the collapse of the pier or piers and allows the building to fall to the ground.
The support head of the standard pier is not mechanically attached to the mainframe in any way. It resists sideward movement or stress only by dead load friction. When the building supported by standard piers is subjected to sideward motion or stress which exceeds the dead load friction resistance to movement, the building only has to move an average of 2" to leave the pier. There are a considerable number of documented cases where manufactured buildings have simply, over a period of time, vibrated off the pier support heads and fell to the ground because of this lack of mechanical attachment.
These negative characteristics of standard piers have been particularly evident in areas where such building are subjected to earthquake related ground movement. Experience in California over the past twenty years has shown that standard piers under manufactured buildings have a very high rate of failure due to the design flaws detailed above. There has been and currently is a critical need for the invention of a product that combines the ease of and convenience of pier type installations with a safer and more reliable design that reduces or eliminates the shortcomings of the currently used pier supports as well as providing the resistance needed to vertical, horizontal and lateral loads and load accelerations which such buildings may be subjected to during earthquakes and other forms of extraordinary stress loading conditions. Our invention does just that.
The current practice to provide a safe and stable foundation for a manufactured building is to install a standard pier type mainframe foundation then augment that system with a separate earthquake bracing system designed to resist horizontal or lateral movement. The cost of such a combined system averages from $4,000.00 to $7,500.00.
Using our system as an earthquake bracing and support system that augments a standard pier foundation would save the consumer an average of $900.00 to $3,000.00 over conventional earthquake bracing systems. Our device combines the functions of both the standard pier support and earthquake resistive bracing at a considerably lower cost to the consumer.
All patent rights on standard pier foundation devices as described herein have long since expired.
Earthquake braces are available in various configurations and designs. Patents have been previously granted on the following earthquake braces: Quakebrace.TM., patent #4,417,426, Gusguard.TM., patent #4,262,149, and Safe-T-Brace, patent #4,373,307. None of the above cited examples of prior art are in the same class of product as our invention, but are products which only partially perform the functions of our invention.
Our invention consists of a fabricated base consisting of an "X" design base plate having a much broader "footprint" than conventional piers, attached by means to a base non-metallic, moisture resistant base pad or footing. At the top center of said "X" design base plate is attached a metalic vertical support housing. Lateral legs are attached to the outside ends of the "X" base plate and run at approximately 45 degree angles to the upper portion of the outside walls of the vertical support housing and there attach by means, thus forming an extremely strong pyramid shape which has the ability to transfer vertical load directly to the ground at its center in a direct line with the load it supports rather than transferring that load at a tangent angle down the legs only, as is the case with standard type pier supports. The actual vertical load bearing member of our device is a fabricated metal tube of varying lengths, the bottom end of which is inserted inside the vertical support housing and the top end of which terminates at a point above the top of the vertical support housing and has means at its top for the attachment of the mainframe support head. The mainframe support head consists of a formed metalic channel to the bottom of which is attached a threaded rod with adjustment nut which threaded rod attaches by means to the top of the vertical load bearing member. The upright flanges of the mainframe support head are provided means for the mainframe support head to mechanically attach and/or clamp, by means of our clamping devices, to the mainframe chassis member of the manufactured building our device supports. In addition to acting as a support structure for the building, our invention can also be used to level the building due to the variable lengths of the vertical load bearing member and the height adjustability of the mainframe support head by means of the threaded rod and nut.
This invention solves the problem of many shortcomings of the standard pier and doubles as a highly effective bracing and stabilization device for resistance to ground motion, vibration and other types of vertical, horizontal and lateral stresses and loads that can cause standard piers to fail and allow the manufactured building to fall. Its fully adjustable height design gives it the added versatility to act as a fine leveling device as well. Our invention considerably reduces the cost of manufacture of earthquake bracing and consequently the end cost to the consumer of a stable, reliable and extremely strong foundation for their manufactured building when compared to prior art and current installation practices.